You cannot reverse the refund,  but when you see tracking has confirmed delivery,  you can send the buyer a polite message explaining as you have tracking now showing delivery could they kindly repay you the cost of the item.

This cannot be done through eBay now,  if the refund was done through an eBay case.

The buyer needs to repay you via a cheque,  bank transfer a PayPal Friends and Family payment,  or you can send them a PayPal invoice for the amount.

Nothing to enforce the seller to repay you, but most peeps are honest,  and would not want an item for nothing.

  If  PayPal is used,  email addresses need to be exchanged, this can sometimes be found with the order details >>  Show Contact Info.    If not and you need to ask the buyer for this,  make it very, very clear in your eBay messages,  as eBay do read these,  the reason for these exchanges.   Make it clear it's not to be used for an off eBay sale.  

@andre_90079